What is a prism color separation system?

Dichroic prism is a kind of prism that can split light into two beams with different wavelengths (colors). Usually, according to the wavelength selectivity of light or the reflection and refraction of optical coating, it consists of one or more prisms, and the required wavelength can be selected. That is, some surfaces of prisms are used as dichroic filters and beam splitters in many optical instruments. (Refer to the etymological terms of dichroism. )

One application of dichroic prism is for high-quality digital photography or as a camera. A three-color prism group consists of two dichroic prisms, which can be divided into three combinations: red, green and blue, so it can be used as a CCD array.

The picture shows the typical configuration of the equipment. A beam of light enters the first prism (a), and the beam with blue component is reflected by the coating (F 1) of the low-pass filter. Blue light is high-frequency light with shorter wavelength, while low-frequency light with longer wavelength can pass through. Blue light is totally reflected by the other side of the prism, and then emitted by the prism A. The rest of the light enters the prism (B) and is split by the second coating (F2), red light is reflected, and light with shorter wavelength can pass through. The red light is also totally reflected through the small air gap between prisms A and B, and the remaining green light enters prism C. ..

Such a three-color prism combination can also be applied to the projector in turn, combining red, green and blue into a color image.